Catheters are commonly used to provide quick and direct access to a patient's blood stream. Such range from a basic intravenous line in a patient's arm to more critical-care central venous catheters (CVC). Catheter maintenance can be costly and troublesome, especially for all but the simplest short term catheters which merely continuously drip fluid into a patient's arm vein.
For example, a CVC is inserted by a surgical procedure and extends to a location very near the heart. A CVC is often left in place for a relatively long time. The skin entry point is kept covered by a carefully monitored dressing. Because of the direct nature of access to the blood stream, infection control when dealing with CVCs is of utmost importance. In most institutions, only registered nurses and doctors are allowed to perform procedures relating to CVC access.
CVCs include an external access lumen having a terminus injection/withdrawal port which typically includes a Luer-lok connector. One form of an injection port which is mated with the connector is a pierceable rubber membrane. Fluid transfer through such a port requires first cleaning the pierceable membrane with alcohol and/or Betadine, and then inserting a hypodermic syringe needle through the membrane to provide direct access to the blood stream. Alternately, such an injection port can be removed enabling a syringe tip having an appropriate luer-lok connector to be directly connected to the catheter access lumen.
CVC access lumens can become clogged by clotted blood. The access lumens are kept free from clots when not in use by injecting a heparin solution into them, which is commonly referred to as a heparin lock. Heparin is a protein material which acts as a blood anticoagulant to interfere with blood clotting. Before withdrawing a blood sample from a CVC, the heparin and the blood containing heparin which is in the catheter is first withdrawn. Also depending on the patient's condition and type of catheter, it is sometimes desirable or necessary to withdraw heparin from the catheter before injecting a medication through the catheter.
There are significant risks associated with transferring fluid through a CVC. One risk is that of microbial infection. Another significant risk is that of air embolism. Both of these risks are potentially life-threatening and increase significantly with each access through the CVC access lumen, especially when such an access is by way of a needle and pierceable membrane. Compounding these risks is the fact that a single medication injection procedure or a single blood collection procedure can require four or more separate connections to the CVC access lumen, one for each separate fluid injection and withdrawal. In some cases, the CVC is used for medication injection or blood withdrawal as many as four to six times each day. Thus, as many as twenty-four CVC connections are required every day, with a corresponding number of opportunities for infection or air embolism. Over the period of a month, the CVC could present over 700 opportunities for life-threatening events to occur.
As an example, a simple medication injection procedure requiring heparin withdrawal includes the following steps. First, the pierceable membrane of the injection port must be cleaned with alcohol. The success of this step is highly dependent on the skill of the care-giver and is subject to mistakes caused by carelessness or inattentiveness. A needle of a waste blood withdrawal syringe is then inserted through the membrane. The syringe is operated to withdraw the heparin-containing blood from the CVC. Then, the treatment protocol requires a saline syringe to be utilized to flush the catheter. A medication syringe is then prepared, its needle inserted through the pierceable membrane, and medication injected into the CVC. Subsequently, another saline flush syringe is prepared and utilized to carry all the medication into the patient's blood stream. Finally, a syringe containing heparin is injected into the CVC through the pierceable membrane to re-establish the heparin lock. If all this is done quickly and correctly, the catheter should not clot, no air embolism should result, and the patient shouldn't get an infection.
Withdrawing or collecting blood requires similar steps. First, all heparin-containing blood is withdrawn from the CVC transfer lumen by injecting a needle through the pierceable membrane and withdrawing blood into a syringe. The needle of a waste blood withdrawal syringe is then inserted through the membrane, and the syringe is operated to withdraw heparin-containing blood from the CVC. After the heparin-containing blood is completely withdrawn from the catheter, the waste withdrawal needle is removed and a needle of another syringe is inserted to withdraw non-heparin contaminated blood. Then a normal saline flush of 20 milliliters is injected, followed by another heparin flush with yet another needle and syringe.
As is apparent from the above discussion, another problem with standard CVC access procedures is that the various solutions and syringes needed to access a CVC are supplied separately. Often, a nurse must track down each piece of equipment separately. This can be a costly and time consuming process. Furthermore, even after proper equipment is found, such equipment is often not designed to work together as a system.
In part because of this, CVC procedures are performed only by registered nurses or doctors, with the procedure consuming a large quantity of their valuable time. The patient and other care-giver personnel are often forced to remain idle while waiting for the qualified persons to find time to provide the catheter access service.
As an additional complication, access to a CVC by needle gives rise to a potential source of injury and infection to the care-giver through contact with the needle. This is particularly important when the patient being treated has a dangerous infection, such as HIV or hepatitis. Often, the care-giver and patient are unaware that an infection is present.
In addition to CVC maintenance and operation as described above, it can be highly desirable in emergency situations to get a plurality of medications quickly into a patient's bloodstream through a CVC or other catheter. It would be highly desirable in such situations for the care-giver to have a catheter access system which facilitates multiple accesses to the catheter.
Our U.S. Pat. No. 5,308,322, formerly U.S. patent application Ser. No. 08/048,906, is hereby incorporated by reference.